Inverter/UPS/Hybrid standby power use

completelycharged

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Have been looking at a few UPS/inverters and one of the interesting elements is the parasitic load (the load the inverter uses even if these is nothing connected to it). With a limited energy supply the choice of inverter can get interesting as to which one to use, at the moment I have a 2200VA UPS switched on 24x7 but I am realising that this is not going to work in winter (or when I don't have a surplus of power) because the UPS unit on it's own uses around 75W, which is nearly 2kWh per day or nearly half of my 24x7 equipment.

With this in mind, I'm trying to findan option that will work and has minimal wasted energy. My smaller 24V Belkin unit is very good, but limited load so wondering what route / inverter, ideally 48V...

This is my list so far... will update it

Make Volt Model Rated VARated W No Load use
APC 48V Tower 2nd Gen 2200VA 1980W 75W (approximate)
APC 48V 1U rack 3rd Gen 2200VA1980W 60W (approximate)
Belkin 24V ?? 2000's 650VA 350W ? 5W (approximate)
MGE 72V ?? old 3000VA 80W (approximate)
Eaton 36V Evolution 1550 1550VA 1100W 20W (need to measure again)


The limited power location is a 20ft container with solar on top and a small wind turbine closeby, so every watt counts...
 
I love the grid charging f a UPS but I also hate the Low Load losses. One thing I have noticed is that once you hit that magic 75W of Load the losses diminish greatly. So if you have a constant load of at least 50W the APC will be just fine but when zero usage it sucks. For my setup if I cannot find a good Low Loss UPS I will be forced to go the route of an inverter and separate charging system
 
The lower power non server grade UPS units seem to have lower losses. The Belkin unit I have is great, but it is limited to 300W or so (will check on my next trip) and have thought about using multiple units. Tempted to buy a used non server 1500VA sized UPS but they seem a little more rare (at a siensible price).
 
I gotta check the 500VA APC I have here and the 1500VA triplite 36V to see how they are
 
Schneider SW4048 Inverter/Charger
Self consumption : 27 Watts
Source : http://www.backwoodssolar.com/schneider-conext-4000w-48v-inverter-120v-240v-ac

Interesting bit : "Stacking two units together doubles the inverting and battery charging capacity; BUT surge capacity is NOT doubled when stacking this inverter."
Do the other PIP units have stacked/parallel surge capacity greater than a single unit ?

Power Star IR3048C 3000W : 56.7V 1.6A = 90W standby !!!
 
Reading through a very long thread on another forum (only part way through 138 pages...) the higher standby load on some inverters is there by design.... The reason is so that the transformer when coupled with a smaller capacitor then also acts as a line filter to smooth out the primary input switching from the MOSFET's. Plus, having a badly selected transformer does not help if the voltage is saturating the transformer and creating additional magnetic losses....

Inverters with toroidal transformers will also have far lower standby losses.
 
Ill try and test what I have sitting around for your list I have a couple of those older black pure sine APC Smart-UPS 1000VA and 1500VA units and I was a bit curious myself.

I have a <300 watt load project for my office computer and networking gear, but after reading this thread, I might be better off just getting a small Victron inverter for $120-130 bucks.

Im going to end up paying for it one way or another either efficiency or have to add more capacity just for a high idle load.
 
I'm now looking at toroidal transformers as a modification option.

Just switched off the inverter (IR3048C) after it had been on for about 4 hours (forgot to switch it off after seeing it it would run the 3ph circular saw with a soft starter and it does!) and the unit was warm... reading 55C, on idle, nothing plugged in... I'm now having second thoughts on which inverters to use or to make sure I switch them on/off only when I need them. Unless I'm cold and need the heat :p
 
completelycharged said:
Reading through a very long thread on another forum (only part way through 138 pages...) the higher standby load on some inverters is there by design.... The reason is so that the transformer when coupled with a smaller capacitor then also acts as a line filter to smooth out the primary input switching from the MOSFET's. Plus, having a badly selected transformer does not help if the voltage is saturating the transformer and creating additional magnetic losses....

Inverters with toroidal transformers will also have far lower standby losses.
Hi i'm new in this forum, reading your posts i'm wondering and i have a question, how to wire a 1 secundary and 1 primay toroidal transformer 230v to a Apc with the same characteristcs, i'm asking if is possible replace the 2 APC's original transformers have 4 wires, with a normal torroidal transformer. Thank you in advance.
 
Your toroidal transformer would need 2x primarywindings to work the same as the APC's original one.
This is dueto the APC's circuit design which will havetwo halfs.
Check the APC circuit, it will join the two primary windings in series, with the centre tap connected tobattery +ve.

Maybe try to find the right transformer with 2x primary + 1x secondary.

You might be able toadd you own new 2x primary windings as not too many turns are needed, maybe only approx 10.
To be sure, try to (carefully!) measure the turns ratio of the APC original transformer, eg from one primary to the secondary.

Note that toroidal transformers saturate much more easily than the E-I core type because there is less air gap.
 
Redpacket said:
Your toroidal transformer would need 2x primarywindings to work the same as the APC's original one.
This is dueto the APC's circuit design which will havetwo halfs.
Check the APC circuit, it will join the two primary windings in series, with the centre tap connected tobattery +ve.

Maybe try to find the right transformer with 2x primary + 1x secondary.

You might be able toadd you own new 2x primary windings as not too many turns are needed, maybe only approx 10.
To be sure, try to (carefully!) measure the turns ratio of the APC original transformer, eg from one primary to the secondary.

Note that toroidal transformers saturate much more easily than the E-I core type because there is less air gap.
Hi, Redpacket, i do not understand very well about eletronic, let explain my situation; i have some 28v 230v toroidal transformers. Reading the posts i tought if possible to use them to low the losses on APC UPS. And make some tests. But i'm not sure how to use them. Thank you so mutch.
 
jdeadman said:
I love the grid charging f a UPS but I also hate the Low Load losses. One thing I have noticed is that once you hit that magic 75W of Load the losses diminish greatly. So if you have a constant load of at least 50W the APC will be just fine but when zero usage it sucks. For my setup if I cannot find a good Low Loss UPS I will be forced to go the route of an inverter and separate charging system

Before solar, I had apair of APC 3000 towers and 9 APC1500s around the house - for last 15-20yrs because of power company surges / outages have damage computer equipment in the past. I'm have several servers and so it was to incorporate/rely on UPSs in my life experience.

Since solar, I have consolidated to a pair of APC 3000 towers and run a set of 120v plugs thru the house so that the individual APC 1500s are no longer needed. Because of the consolidation, the remaining APCs have a steady load all the time...

So you're saying that since I have load all the time, I have 'inadvertently' negated the idle power burn issue? That sounds great. And this might be a solution for others... e.g. consolidate/arrange your solar project so you're UPS(s) have constant load? Mine is specifically an APC type of UPS.
 
you will always have more energy used from the batteries than is going our the AC lines. it's just the conversion losses. It's lower once you hit a threshold but never will be zero. Generally with my APC I was 1.5Amp @28V zero load (42W) to at 50% load (500W) the Batteries would pull about 520W so 20 Watts of Loss instead of the 42W of zero load. Now that i have more time with a MPPSolar LV2424 inverter I can bank on 1kWh of losses per day as long as I have load on in the inverter.
 
1kwh per day is nothing. I run 7+kwh per day just in idle load :) Then another easy 4-5 in conversion losses...
 
7!!!!!!! OUCH But that is the price we pay for generating that amount of power. I'm only running a 2.4kw single phase inverter. Way different in component count to your 3 phase Beast mode inverter
 
OffGridInTheCity said:
jdeadman said:
I love the grid charging f a UPS but I also hate the Low Load losses. One thing I have noticed is that once you hit that magic 75W of Load the losses diminish greatly. So if you have a constant load of at least 50W the APC will be just fine but when zero usage it sucks. For my setup if I cannot find a good Low Loss UPS I will be forced to go the route of an inverter and separate charging system

Before solar, I had apair of APC 3000 towers and 9 APC1500s around the house - for last 15-20yrs because of power company surges / outages have damage computer equipment in the past. I'm have several servers and so it was to incorporate/rely on UPSs in my life experience.

Since solar, I have consolidated to a pair of APC 3000 towers and run a set of 120v plugs thru the house so that the individual APC 1500s are no longer needed. Because of the consolidation, the remaining APCs have a steady load all the time...

So you're saying that since I have load all the time, I have 'inadvertently' negated the idle power burn issue? That sounds great. And this might be a solution for others... e.g. consolidate/arrange your solar project so you're UPS(s) have constant load? Mine is specifically an APC type of UPS.
Hi i'm wondering if possible charge the 96v battery bank directly from 3 solar pannels (VPM 37.83) with no carge controller. (37.83x3=113.49/8=14.18.) The razion of my question is; i need to use one UPS that works from 92dc aup to 120dc. This Ups is just for a few hours a week. Thank you.
 
It's not advised as Charge controllers can slow the current when the batteries get full vmp is not the VOpen Curcuit that can be much higher and therefore overcharge your batteries
 
NJM said:
Hi i'm wondering if possible charge the 96v battery bank directly from 3 solar pannels (VPM 37.83) with no carge controller. (37.83x3=113.49/8=14.18.) The razion of my question is; i need to use one UPS that works from 92dc aup to 120dc. This Ups is just for a few hours a week. Thank you.

Quick answer: No.

Longer answer: Not really. You "could" directly connect, but you will be highly inefficient of the power delivery. Also the solar panel output will equalize to the voltage of the batteries after awhile, so the batteries won't get fully charged. Also, during the night time, the solar panels will actually drain the batteries (as the solar cells are actually a type of LED, infrared tho). And if you put diodes in place, this drops the effective output of the panels.
Using a charge controller, it regulated the voltage output to be just above the battery voltage so it's always pushing into the batteries until they are full. And, as jdeadman states, the charge controller also regulates the amps delivery.

Charge controllers, especially MPPT, will try to find the best combination of voltage and amps pulling from the panels to give the most watts to the batteries.

A really basic MPPT charge controller can be had for <$30USD. MPPT would be preferred over PWM as it's more efficient. But even PWM would be better than direct connection.
 
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